The invention relates to a protective device for a motor vehicle. Such a protective device may include an airbag, at least one section of which can be inflated in order to protect a vehicle occupant located in the interior of a motor vehicle, the inflatable section of the airbag being formed by two layers of woven fabric which are connected to one another along a peripheral edge, the airbag being configured so as to form a curtain next to at least one window pane of the motor vehicle so that the one layer of woven fabric faces the window pane and the other layer of woven fabric faces the interior of the vehicle, and the two layers of woven fabric being additionally connected to one another outside the peripheral edge. In addition, the protective device comprises at least one gas generator for inflating the airbag by introducing a flow of gas into the at least one inflatable section. This protective device is used especially to protect the head of a vehicle occupant, for example in the event of a side impact or in the event of a rollover.
DE 198 16 061 A1 discloses an airbag arrangement for a motor vehicle, which comprises an airbag which is configured so as to be inflated and form a curtain in the event of an accident occurring. The airbag is composed of two layers of woven fabric which are connected to one another, one of which facing, in the inflated state, the side of the vehicle bodywork and the other facing the interior of the vehicle.
In order to form an airbag, the two layers of woven fabric are not only connected to one another at the edge but also at additional connecting points so that elongated, vertically extending chambers are formed along which the gas from the gas generator flows into the airbag.
A further airbag arrangement which is configured so as to form a curtain next to a vehicle occupant and has vertically extending chambers is known from WO 96/26687 (incorporated by reference herein).
The invention is based in part on the object of providing a protective device for a motor vehicle of the type mentioned above, while having a simple design, and is defined by reliable protection of the vehicle occupants, which is to be ensured in particular by suitably introducing the gas into the airbag.
According to an embodiment of the invention, the airbag includes two layers of woven fabric connected around a peripheral edge and at additional connection points. The additional connecting points at which the two layers of woven fabric of the airbag are connected to one another are arranged and embodied in such a way that at least a part of the flow of gas which is introduced in order to inflate the airbag can be directed along the peripheral edge at which the two layers of woven fabric are connected to one another to form an airbag.
By virtue of the fact that the gases flowing into the section of the airbag which is to be inflated are directed along the peripheral edge of the section, this airbag section is firstly filled with gas along its outer circumference and thus made rigid. As a result, the section of the airbag which is to be inflated is made rigid at an early point so that the protection of the vehicle occupant also starts at a correspondingly early point.
The flow of gas is advantageously directed along an annular path which is limited on the outside by the peripheral edge of the corresponding section of the airbag and on the inside by the additional connecting points between the two layers of woven fabric of the section.
Here, the additional connecting points can form, on the one hand, a continuous, linear internal limitation for the flow of gas. On the other hand, it is possible to provide that the additional connecting points form an internal limitation which comprises a plurality of sections which are spaced apart from one another and at which the two layers of woven fabric are each connected to one another.
According to one embodiment of the invention, the flow of gas is directed at least partially along an essentially closed, annular path. According to another embodiment, the annular path is embodied in an essentially helical shape.
The two layers of woven fabric can be connected to one another along the peripheral edge of the airbag section in one piece and/or using attachment means, for example using seams. If the two layers of woven fabric which form the envelope of the airbag are formed by an additional woven fabric blank, the two layers of woven fabric are connected to one another in the region of a turn-over edge in one piece and in the region of the other edge using seams or the like.
The additional connecting points between the two layers of woven fabric which are intended to guide the flow of gas along the outer edge of the airbag can be formed, for example, by means of seams or by means of straps.
In one preferred development of the invention, the airbag has a plurality of inflatable sections which are spaced apart from one another and which can each be configured in a way according to the invention. The individual sections may be assigned, for example, to a front side window, the B pillar of the motor vehicle and a rear side window.
In order to permit a lateral curtain to be formed when the airbag or at least a section of the airbag is inflated, the airbag is preferably attached along the roof-side edge of the door frame of the vehicle. The flow of gas is then preferably introduced from the roof side into the airbag or the inflatable section or sections of the airbag.
In order to ensure that a sufficiently large part of the flow of gas which is introduced into the airbag or the corresponding section of the airbag is directed along the peripheral outer edge, the additional connecting points are embodied and arranged in such a way that a linear vertical flow of gas is possible from the roof-end edge region of the corresponding airbag section to the opposite, bottom-end edge region of the airbag section only in a small partial region of the airbag section. The intention is to prevent the gas easily flowing vertically through the airbag section.
The partial region of the airbag section in which a continuous vertical flow of gas is possible preferably covers less than half of the base area of the airbag section which is defined by the peripheral edge region.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.